[page] 758

Vitality of Seeds.—Several statements have been published on the number of years during which seeds preserved in a dry state have retained their power of germinating, but much less seems to be known in regard to seeds lying naturally near the surface of the ground; therefore you may, perhaps, think the following case, though very far from a striking one, worth publishing. An arable field 15 years ago was laid down in pasture; nine years ago last spring, a portion was deeply ploughed up and planted with trees, and in the succeeding summer, as far as I can trust my memory, plenty of Charlock, which abounds in this neighbourhood, came up; but if my memory plays me false the case will prove so much the stronger. From being badly ploughed the whole of the land in the course of the year became covered with Grass and coarse weeds, and has remained so ever since, and the trees have now grown up. It is very improbable, from the well known habits of the Charlock, that it could have grown in the little wood after the first year or two; and though almost daily visiting it I have not noticed a plant. But this spring I had some Thorn bushes pulled up, and it was so done that not more than one or two (I speak after comparison) hand's breadth of earth was turned up. To my surprise in July I happened to observe on one of the little patches of earth no less than six dwarf Charlock plants in flower; on each of two other patches three plants; and on the fourth one plant. This made me on July 21st have three separate plots of ground, each 2 feet square, in different rather open parts of the wood, cleared of thick Grass and Weeds, and dug one spit deep. By August 1st many seedlings had come up, and several of them seemed to be cruciferous plants; so I marked with little sticks 11 of them on one of the beds; six on the second bed; and five on the third bed; two or three died, all the rest grew up and proved to be Charlock. I can state positively that no Charlock was growing near these beds; and I do not believe there was any within a quarter of a mile, as the little wood is surrounded by Grass land. Now, to my mind, this seems good evidence that the Charlock seed had retained its vitality within a spit's depth of the surface during at least eight or nine years. In most cases, when plants spring up unexpectedly, as when a wood has been burnt down, it is not possible to feel sure (as has been remarked to me by Dr. Hooker) that the seeds had not been strewed about during the last year or two by birds or other means. Had the several Charlock plants come up on one spot alone, I should have thought that some accident had brought a pod there, and that I had overlooked during the previous years a few Charlock plants, but it seems to me improbable in the highest degree that on each of the 6 plants,¹ taken by simple hazard, several (in one of the cases 11) seeds should have been dropped by some unknown agency, having been brought from a quarter of a mile distance. But if when the land was ploughed, 9 years ago (or when arable, 15 years ago) the whole was, as I believe, almost covered by Charlock, the seed would have been scattered everywhere, ready to spring up at whatever point the land might subsequently be stirred up. I will only further remark that the power in seeds of retaining their vitality when buried in damp soil may well be an element in preserving the species, and, therefore, that seeds may be specially endowed with this capacity; whereas, the power of retaining vitality in a dry and artificial condition must be an indirect, and in one sense accidental, quality in seeds of little or no use to the species. Charles Darwin, Down, Nov. 13.

¹ Darwin pointed out in his 21 November letter to Gardeners' Chronicle that '6 plants' was a misprint and should have read '6 plots of ground'. See Correspondence vol. 5, p. 502.

This letter was a response to an editorial in the Gardeners' Chronicle no. 45 (10 November 1855): pp. 739-40. See [Darwin] 1844, F1918 and Correspondence vol. 5, p. 502.